Determining whether an employee’s Standard Threshold Shift is work-related for OSHA 29 CFR 1910.95 follow-up purposes and OSHA 300 log recordability purposes requires a distinct, documented professional judgment from the professional supervisor. Not every STS is recordable — only those determined to be work-related under OSHA 1904.5’s work-relationship standard. According to CDC/NIOSH, a significant fraction of apparent audiometric shifts in noise-exposed workers may have partial or predominant non-occupational contributions, but the OSHA presumption of work relationship means the employer must document the basis for any non-work determination.
The Work-Relationship Presumption
OSHA 29 CFR 1904.5(a) presumes a work relationship for any injury or illness occurring in the work environment. For hearing loss, the key question is whether occupational noise exposure was a “significant contributing cause” of the STS. The employer bears the burden of establishing non-work-relatedness if they want to avoid recording the case on the OSHA 300 log.
The work-relationship determination for OSHA 300 log purposes is a professional judgment that must be made by the professional supervisor (licensed audiologist or physician), not by the EHS manager. The professional supervisor evaluates the audiometric pattern, the worker’s occupational noise exposure history, non-occupational noise history, and medical history to determine whether occupational exposure was a significant contributing cause. Document the professional supervisor’s reasoning in the HCP records.
Factors Supporting Non-Work-Relatedness
- Worker’s measured occupational TWA is below the 85 dBA action level — minimal occupational noise contribution
- Audiometric pattern is inconsistent with NIHL (low-frequency loss, fluctuating loss consistent with Meniere’s disease)
- Documented significant recreational noise exposure (firearms, concerts, power equipment use) that exceeds occupational exposure
- Documented medical condition with established hearing effects (Meniere’s disease, acoustic neuroma, ototoxic medication)
- Audiometric pattern shows sudden loss more consistent with acoustic trauma than gradual NIHL
When the professional supervisor determines that an STS is not work-related, the reasoning must be documented clearly in the HCP records. If OSHA later reviews the 300 log and asks why this case was not recorded, the employer must be able to produce the professional supervisor’s written determination with the clinical reasoning that supports it. Undocumented determinations are effectively undocumented compliance decisions.
Frequently Asked Questions
Professional Supervisor Work-Relationship Determinations Documented
Soundtrace Professional Supervisor reviews include documented work-relationship assessments for STSs — providing the clinical reasoning required to support OSHA 300 log recordability decisions.
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